Currently, oxide TFT array substrates mainly have three types of structures: co-planar type, etch stop layer and back channel etching. Co-planar oxide TFTs are widely applied due to the characteristics of relatively simple structure, small damages to active layer, etc. However, in the manufacturing process, the active layer must be formed on a substrate provided with a gate insulating layer and a source/drain metal layer by a patterning process, which will involve the deposition process of an oxide semiconductor and a wet etching process with acid liquor. Both the processes can cause great damages to the formed source/drain metal layer.